Episode 3 could have been the best if it wasn't for the poor dialogue, and some of the plot direction. I'm in love with the themes, like Palpatine's manipulation of all the chess pieces, the change in relationship and eventual battle of Anakin and Obi-Wan, the entire war being one long con job and the end of the golden age of the core worlds, but even I can't defend a lot of the movie's bigger mistakes (NOOOOOOOOOOOOOOOOOOOOOO).
As a kid, it was all about the fights and the magic, but as an adult, I love seeing the more nuanced and complex conflicts, which is why Episode 3, 5 and Rogue One are my favourites so far. They make no illusion that the world is stuff mixing in a lot of grey and grey morality, and it's on full display that people have to do terrible things in the name of what they consider moral. I'm hoping we might see a main-line movie that even questions or blurs the core philosophies of the Jedi and Sith.
And George is a great visual director (if we overlook some of his stupid edits). Star Wars incorporates a lot of amazing cinematography you may not be aware of. His problem is whenever he feels the need to tell instead of showing, and has characters blurt out awkward exposition (and by all accounts, he's incredibly brown town about the way actors deliver their lines).